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Cisco 10008 Router Hardware Installation Guide
OL-0659-13
Chapter 4 Starting and Configuring the Router
Managing System Boot Parameters
Changing the Configuration Register Settings
To change the configuration register settings while you are running system software, perform the
following steps:
Step 1 From global configuration mode, enter the config-register value command to set the contents of the
software configuration register; value is a hexadecimal number preceded by 0x. For example:
Router(config)# config-register 0x2100
Consult the hexadecimal column in Table 4-2 for the possible settings to enter as the 4-bit value
parameter.
Step 2 Exit global configuration mode by pressing Ctrl-Z.
Router(config)# Ctrl-Z
Router#
The new contents of the software configuration register are saved to NVRAM. These new settings do
not take effect until you reload the system or reboot the router.
Step 3 To display the new software configuration register setting, issue the show version command.
Router# show version
.
.
.
#Configuration register is 0x141 (will be 0x2100 at next reload)
Step 4 Save the configuration file to preserve the new software configuration register settings.
Router# copy running-config startup-config
Step 5 Reboot the router.
The software configuration register setting takes affect only after you reload the system. This happens
when you issue the reload command from the console or reboot the router.
Configuration Register Settings
Table 4-2 summarizes the modifications that you can make to the software configuration register. For
detailed information, refer to the Cisco IOS Configuration Fundamentals Command Reference.
Note The factory default value for the software configuration register is 0x2102. This value is a combination
of the following: binary bit 8 = 0x0100, bits 00 through 03 = 0x0002, and bit 13 = 2000.